This is my first Instructable after using many ideas from the site, so go easy on me.
Having owned numerous Yamaha Motorcycles over the years, one thing they have in common is nasty Carb intake rubbers. Over the course of time they go hard, they shrink and the break up. This makes refitting the airbox inordinately difficult and it is usually found unattached the next time you take the tank off. Here is an instructable showing how I replaced the knackered rubbers with sexy Silicon hosing
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Step 1: Step One, the Size of the Problem
First things first, check the diameter of the carb, this will decided the size of hose to order. The carbs on this FZ750 were 52mm, I ordered a length of 51mm hosing.
I then measured the depth of the lip on the original intake rubber, In this case it was 10mm (from the edge to the obvious ridge in the photo. I had a further 15mm to where it butted to the airbox. I then added 5mm to allow for shrinkage and to provide a "push" from the tank to hold things in place more securely
Step 2: The First Cut Is the Deepest
I then set a pair of dividers and scored a line 30mm parallel to the end of the hosing. I went over the score with a Sharpie and proceeded to gouge out the line with the rotary tool. Once a succesful line was scored I went through the pipe with a junior hacksaw. A bandsaw would be a better option but I don't have one of those. It is important to get this cut correct as it needs to firmly butt up and inconsistency in the first cut is amplified on succeeding cuts. I then faced the cuts on my bench grinder
Step 3: The Second Cut Is Just As Deep
Now turning to the original rubber, I rotary tooled the old lip away just above the seam
I then trial fitted the silicon replacements to the airbox. Satisfied with the fit I then placed the new rubbers on the carbs and fastened them down. The airbox was then installed and If I had remembered to buy some more hose clamps I would have secured them to the airbox end.
There you have it, a cheap remedy for an annoying problem